If you are seeing this message displayed when you try to order a layout then this is because:

1. You have designed your layout as a Traditional Matted type AND

2. You have set up the price list for the same template/layout as a Composite type or not set up a price at all.

If you wish to produce the final layout as a Traditional Matted type (with the image in each opening as a separate print) then you need to change the type of your layout to be Traditional Matted (with a brown background).

If you wish to produce the final layout as Composite (with the images and mat together one piece of paper) then you need to change the type in your price list so you can order the layout as a Composite.

For how to do either of these (or order the layout as a once-off), see this KnowledgeBase Article: Ordered Layout not in Composite section in Production.  Note: This article is about swapping from Traditional Matted to Composite type. In your case, you just need to do the opposite!